Hidden controls have been used to provide a user control over an action without the knowledge of others. For example, banks use hidden controls to allow employees to initiate silent alarms when threatened. Such hidden controls are typically in the form of a mechanical button that is hidden from view from the public, for example beneath a counter or desk, yet easily located by the employee by feeling the button without having to look at the button.
It is desirable to be able to use hidden controls that are in locations within plain sight of the public, but are still hidden from view. Such hidden controls may allow designers to create aesthetically pleasing minimalist designs with clean lines and surfaces, without compromising usability.